This invention relates to microfilm readers and more particularly to a desk top microfilm reader which projects microfilm images onto the top surface of a desk or similar horizontal surface.
With the increase in information available and the dessemination of it, and the proportional increase in paper to store the information, microfilm has become a more common storage media. The advantage is obvious. Microfilm can reduce the storage area by a hundred fold enabling large quantities of documents or graphical forms of information to be stored in a small space. The microfilm can take various storage configurations. One form is commonly referred to as microfilm jackets in which individual strips of film are placed between two transparent plastic sheets having channels to accept and retain the film. A second form similar to microfilm jackets is microfiche, in which a piece of photoplastic material approximately 4 inches by 6 inches has the information photographed thereon. Microfiche can also be made by a duplicating process from an original microfilm jacket. The size of the microfiche can vary, however, the concept encompasses placing multiple images on a single card or fiche. Another microfilm has a card with a rectangular cut therein holding an individual piece of film, commonly referred to as an aperture card. The information may also be retained on rolls of microfilm which are stored in cartridges or cassettes for later retrieval.
Microfilm has become a commonly used tool in business, industry, education, and governmental applications. It has reached a point where the individuals within an organization may require personal microfilm readers at the desks of numerous personnel.
The easiest and most commonly used individual microfilm system encompasses the use of microfilm jackets or microfiche stored at the individual user's location. The reason is that the microfiche can be easily stored in microfiche boxes or containers which can store anywhere from several to a hundred microfiche. Furthermore, the microfiche has an operator viewable index along one margin so that retrieval is simple and inexpensive. Present day microfiche readers commonly are comprised of a high intensity lamp, optical means for condensing the light from the lamp and directing the light through the microfiche, and a second set of optics for projecting the film image onto a reading surface. Thus, the recorded image is projected in an enlarged form for viewing by the operator.
Individual microfilm readers have previously been available of several types. One type was a small hand-held reader which operated either with or without a projection lamp. The film was placed between an external light source and an eye piece with a lens, which was held to the viewers eye. The individual images were read through the eye piece. This was a poor means of reading complete documents as it was inconvenient to locate the particular images, and difficult to read the images through this apparatus for any length of time. Other microfilm readers used the high intensity lamp and lenses for projecting the film image onto a reading surface. The reading surface was either a translucent screen in which the image is projected onto the back of the screen and the image is observed on the opposite side of the screen. The second type, called a front projection reader, has the image projected onto the screen surface and the reflected light image is viewed directly.
The conventional microfilm readers were normally housed within a plastic or sheet metal enclosure which aids in excluding ambient light thus improving the image contrast so that the image can be viewed more easily. The enclosure causes conventional microfilm readers to be fairly large, taking up a substantial amount of desk top area. In the typical office setting, the working desk top area is generally cluttered with file trays, papers, calendars, desk blotters, etc., leaving little area for a microfilm reader.
As previously mentioned, one reason for the large size of conventional microfilm readers of the front or rear projection type is that a complete enclosure is required. The operator looks into the hood of the microfilm reader to view the projected image in a front projection device, or looks at the screen in a rear projection device. Due to the size and optical layouts of these readers, a user could not conveniently place such a device in the center of his desk while trying to work on the desk surface or while trying to converse with a person sitting opposite the microfilm reader.
One microfilm reader which was designed and illustrated in U.S. Pat. No. 4,312,578, entitled "Microfilm Reader", projects an image downward onto a work area. When the microfilm reader is not actually projecting an image, a hood rising above the work station has lamps which are energized to illuminate the work surface. Thus, the user can use the reader as a lamp to illuminate the work surface for reading or various other types of work. However, the work surface is part of the overall microfilm reader and work station and is not separable from the microfilm projection part of the device. Also, the image projected onto the work station surface is at a slight angle relative to the horizontal work surface. Furthermore, this device illustrates a fiche which is inserted vertically into the unit and held in the vertical position for projection. Due to the vertical configuration illustrated, a roller system was required to move the fiche vertically, and a sliding fiche carrier system was required for selecting the proper column in the fiche. The major drawback with the device illustrated was that people who commonly use microfilm are not familiar with a device which had a fiche orientation as illustrated. This made it difficult to position the rows and columns while the film was held vertically. The more commonly used microfilm readers hold the fiche in a horizontal plane and move the fiche in that plane for image selection. Thus, the microfilm user is able to find the desired image more easily when using a microfilm reader having the fiche held in a horizontal plane.
It would be desirable to have a microfilm reader having the excellent image characteristics of a convention microfilm reader, and yet not occupy the additional desk area of the conventional reader. It is also desirable to have a microfilm reader which does not include an integral work surface area and is thus more easily portable.